Aged 20, the Barcelona-born player made his debut for the Catalonia national team before joining Spain Under 21s to lift the European Championship title in 2019.
When the international transfer window opens on July 1, Roca will join a trio of compatriots at Elland Road as Diego Llorente, Rodrigo, and Junior Firpo welcome him to West Yorkshire.
Firpo, who played alongside Roca for Spain Under 21s, gave the Whites' new signing some advice before he signed the deal.
"He told me that it's an incredible club," Roca said. It's amazing atmosphere that you can be in this stadium, that the teammates are incredible, the atmosphere that you can breathe in the locker room is incredible."
1. Raúl Bravo
Bravo signed in January 2003 and only made six appearances for the Whites.
Photo: Alex Livesey
2. Pablo Hernández
Hernández became a permanent Leeds United player in August 2016 and made 175 appearances across his Elland Road career.
Photo: Laurence Griffiths
3. Alfonso Pedraza
Pedraza made 14 appearances for the Whites after signing in January 2017.
Photo: Alex Pantling
4. Madger Gomes
Gomes joined in June 2017 and went on to make 2 appearances for Leeds.
Photo: Jonathan Gawthorpe